Why does the Torah repeat Noach's name three times in the first verse of the Parsha?

The Torah describes Noach as Ish Tzadik Tamim, a perfectly righteous man (lit. a righteous man, perfect...). What is the significance to this description?

Why are one's good deeds considered like his children?

Why did Hashem need to destroy the entire world, wouldn't it have been enough to kill all of its inhabitants?